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The explosion happened just outside the prison

A South African police officer has been arrested over last month's attempted jailbreak, in which three inmates were killed.

The officer is accused of passing an explosive device to the prisoners in the court where he worked.

An explosion ripped through the van carrying the inmates as it returned to Johannesburg Central Prison. Two escaped but were quickly recaptured.

The officer faces three charges of murder and 29 of attempted murder.

He will also be charged with unlawful possession of explosives and aiding and abetting escape from lawful custody, said Independent Police Investigative Directorate (IPID) spokesperson Moses Dlamini

Mr Dlamini said that the 29-year-old officer would appear in court on Wednesday.

Four prisoners have already been charged over the attempted jailbreak, which South Africa's National Commissioner of Correctional Services Tom Moyane described as South Africa's most "daring escape attempt".

The explosion took place just metres from the prison, as the bus carrying the prisoners returned from court in Randburg, about 40km (25 miles) away.